I bought a pair of Ugg boots in the early-'90s. Still have them. They’ve always slipped a bit, so that’s why I don’t wear then a lot and why they’ve lasted so long. Gotta figure out a way to tighten them up.
Thicker socks or boot belts.
I’m kinda cheap so I just use a couple of matching dog collars I got on sale but there are some really fancy boot belts out there.
ETA My UGGS usually last about 7-9 years a pair, but I wear them anytime I can and I don’t care that I look like I have ugly muppet feets, I am comfy. /wiggles toes happily in 5 year old UGGS/
I love my Uggs. I got my first pair in the early 90s and wore them every day in most casual settings until the first pair wore out. I’ve still got the second pair I purchased in the early 2000s.
I kind of set them aside when I learned there is an unfortunate stigma attached to wearing them in certain parts of the world. Notably, Australia.
When I visited my then-boyfriend-later-husband-now-late-husband in Aus, I naturally packed my favorite comfy Uggs. First day of proposed sightseeing, I pulled on my jeans, casual top and my Uggs. TBLHNLH gave me a look of sheer horror and disgust.
“What?” I said.
“Why don’t you just don a pink track suit while you’re at it?” he replied.
I gathered from his expression that I was committing a low class fashion faux pas in Australia.
He’s been gone for more than 15 years, and I’m not fashion conscious these days. Maybe it’s time to drag 'em out again.
Yeah, wearing uggs OUTSIDE the house in Aus is definitely bogan material. Like moccasins back in the 1980’s, they are a social statement of the worst kind!
But uggs are friggin grouse. I miss mine, had to give them up when I moved from frigid Melbourne to the tropics. And they were the good ones, costing app $250…but they ended up in the Goodwill shop, hopefully purchased by someone who was migrating south. 
LOL, so I learned! I thought it was pretty hilarious, because I was living in a fashion-conscious area of California at the time, and everyone wore them out and about there. Never took them back to Australia again, that’s sure!
I’m sorry you gave yours up, but it makes sense under the circumstances.